COLORDiamond color is based on a scale from D to Z. The more color there is in a diamond, the more yellowish tint you will see. While this is not necessarily a bad thing, public opinion has decided those with less yellow equals better. Grades D, E, and F are considered colorless and are of course the more valuable. G, H, I, and J colored diamonds are where you find a good value and very miniscule traces of yellowing, not seen by the untrained eye. K, L, and M colored diamonds show a faint yellow tint, but not in every circumstance. It really depends on your angle of view, the lighting, the mounting, and the size of the diamond itself. Once you go below N, plan on noticing a yellow tint on any diamond bigger than a 1/2 carat even in the best of conditions. While not to scale, use the chart below to see how color degrades.
Diamonds can also be colored, such as bright yellow, blue, pink, black, green, and even red. These are considered fancy colored diamonds. These diamonds are rarer than white diamonds and are sometimes more valuable.